VM2 Sandbox Breakout via Inspect Function Allows Remote Code Execution

A critical sandbox escape vulnerability has been identified in VM2, a popular JavaScript sandbox environment for Node.js. This vulnerability, assigned CVE-2026-24781, stems from the improper handling of proxies within the inspect function. By exploiting this flaw, an attacker can bypass the VM2 sandbox and execute arbitrary code on the host system. The vulnerability affects VM2 versions 3.10.3 and earlier. This allows for remote code execution under the assumption that arbitrary code can be executed inside the context of a VM2 sandbox. Defenders should update to the latest version and implement the provided detections.

Attack Chain

1. The attacker executes code within the VM2 sandbox, leveraging the inspect function to log details of objects.
2. The inspect method unwraps proxies to access object details.
3. The attacker uses this.seen of the stylize function to extract unwrapped values, gaining access to the internal proxy handler of VM2.
4. The attacker accesses the sandbox object within the proxy handler. Accessing the handler is wrapped by a VM2 proxy.
5. The wrapped sandbox object is given into the sandbox.
6. The attacker writes a wrapped host object to the wrapped sandbox object.
7. The attacker reads the raw host object from the raw sandbox object, bypassing the proxy bridge.
8. The attacker utilizes the child_process module to execute arbitrary commands on the host system, such as creating a file named pwned.

Impact

Successful exploitation of this vulnerability allows attackers to perform Remote Code Execution (RCE) on the host system where the VM2 sandbox is running. This can lead to complete system compromise, data exfiltration, or denial of service. Given VM2’s usage in various applications for untrusted code execution, the impact could be widespread.

Recommendation

• Upgrade to the latest version of vm2 to patch CVE-2026-24781.
• Deploy the Sigma rules provided below to detect potential exploitation attempts.
• Monitor process creation events for suspicious commands executed by Node.js processes as highlighted in the attack chain.